Will chewing on a lemon help you lose weight like Naomi Campbell - or leave a bitter taste? Expert verdicts on the diets celebs swear by

Celebrity health tips and diets were recently slammed as nonsense by the charity Sense About Science. But are they all useless? CHLOE LAMBERT asked SIAN PORTER, consultant dietitian and spokesperson for the British Dietetic Association, for her verdict...

THE BLOOD TYPE DIET

Celeb fans: Liz Hurley, Cheryl Cole and Hugh Grant

Cheryl Cole’s famously slender frame was tribute last year to her following the book Eat Right 4 Your Type.

The theory is that lectins — a type of ­protein found in dairy, meat and wheat — react differently with each blood type, ­causing a range of problems from weight gain to indigestion and sluggishness.

Are they actually eating right for their type? Cheryl Cole, left, and Elizabeth Hurley follow a diet based on their blood group but there's no evidence it works

People with blood group A should eat more vegetarian foods, eliminating red meat and dairy. Group B types should cut out wheat, but will thrive on dairy products. Those with blood group AB can eat a diet in between blood types A and B. Blood O types (the most common) need a meat-rich diet.

READ: Eat Right 4 Your Type by Peter D’Adamo.

EXPERT VERDICT: ‘There’s absolutely no evidence that blood type has a role in digestion. Cutting out a major food group is bad news for health and energy levels.

'It’s true that some diets work for one person and not for another — but that’s to do with your genes, your starting point and how active you are, not your blood type. Many of these diets are simply calorie-cutting dressed up with a sexy name.’

THE CLEAN PROGRAMME

Celeb fans: Gwyneth Paltrow and Donna Karan

Short term solution: Detox diets favoured by Gwyneth Paltrow can't be sustained

This is a three-week detoxification programme based on whole, organic, plant-based foods.

Unlike many other detoxes, it allows a small amount of solid food — Gwyneth Paltrow has said this meant she was still able to concentrate on work and exercise.

The diet prescribes two liquid meals a day (such as soups or smoothies) and a solid one in between.

READ: Clean by Dr Alejandor Junger.

EXPERT VERDICT: ‘The Slim Fast diet shows that some approaches based on liquid eating can be successful and at least this diet uses everyday food and drinks.

‘Hopefully you could add some dairy to the soup and a handful of oats to the smoothies to keep some kind of balance in your diet, but you’d be at risk of losing out on iron.

'Yes, this could help you lose weight, but it’s only a short-term solution.’

THE ATKINS 2 DIET

Celeb fans: Angelina Jolie and Brad Pitt

The
Atkins diet is based on the principle of cutting carbs and eating more
protein.

This is said to switch the body into a state of ketosis, where
your body, starved of carbohydrate for energy, starts to burn the
body’s fat stores.

The latest version of the Atkins diet claims
to be healthier because it allows small portions of ‘good’
carbohydrates such as wholemeal bread and brown rice.

READ: Dr. Atkins’ New Diet ­Revolution, Revised Edition

EXPERT VERDICT:
‘This is slightly better than the original Atkins because you’re
allowed small ­portions of healthy carbs, but I wouldn’t condone any
diet that cuts out a whole food group.

‘Yes, you might lose
weight in the short term, but you’ll have all kinds of side-effects
from cutting out carbs, such as bad breath and indigestion.

The theory behind a raw diet is that when food is cooked above 46c, it loses essential enzymes that aid digestion and the absorption of key nutrients. (Anything below 46c is considered raw; water simmers from 60c).

Followers make sure 80 per cent of their food is uncooked and use methods such as soaking nuts and dried fruits to ‘wake up’ their enzymes, plus ­juicing fruit and vegetables.

They say this leaves them feeling healthier with more physical and mental energy.

READ: The Raw Food Detox Diet by Natalia Rose.

EXPERT VERDICT: ‘Heat does destroy some nutrients, but it’s a bit of a myth that all foods are best eaten raw.

‘Some veg, like carrots, are actually better cooked because it breaks down the cell wall of the plant and releases the nutrients.

‘The diet is heavy on vegetables and so is very low calorie; in theory, it could help you lose weight — but it’s labour intensive and there’s a lot of chewing to be done.

'One thing you could take from it, however, is not to murder your ­vegetables — preserve the goodness by cooking them in just a little water and for a minimal time.

‘These types of diets are not suitable for children or pregnant women because they cut out food groups such as protein, essential for the growth of new tissue.’

THE 30 PER CENT FAT DIET

Works well: Eating moderate fat like Marcia Cross instead of cutting it out altogether will aid weightloss

Celeb fans: Desperate Housewives star Marcia Cross

Some evidence suggests the best route to keeping off weight long-term is to make a moderate fat restriction (rather than completely cut it out), where fat accounts for no more than 30 per cent of your total calories.

Followers either count up their daily fat gram total or follow an eating plan where all foods are very low in fat.

Healthy (unsaturated) fats are essential for overall health and should not be restricted to a ­percentage less than 20 per cent.

EXPERT VERDICT: ‘This would work well. Gram for gram, fat has twice as many calories as protein or carbs, so if you cut down you can dramatically lose calories.

‘However, you still need some fat in your diet to get essential ­vitamins A, K and D, and essential fatty acids.

'A totally non-fat diet would be dry and difficult to stick to — cutting down to 30 per cent fat, and choosing only unsaturated fats, is much better.’

THE DUKAN DIET

Celeb fans: Jennifer Lopez and Katherine Jenkins

Like the Atkins Diet, the idea is that by shunning carbs and sticking to protein you can accelerate weight loss.

It promises fast weight loss in four highly organised stages. The first phase is one to ten days of eating only proteins such as meat and fish (limitless amounts).

In the second phase you alternate protein days with protein and vegetable days, and in the third stage gradually reintroduce small portions of carbohydrates and fruits.

In the final maintenance phase, you can eat what you like, but must eat protein only for one day each week for the rest of your life.

Hard to follow: The Dukan Diet used by Jennifer Lopez, left, and Katherine Jenkins is confusing

READ: The Dukan Diet by Dr Pierre Dukan.

EXPERT VERDICT: ‘Protein has a satiating effect and helps you feel full. But if you eat too much of it and don’t have enough fluid, it can put pressure on your kidneys, which process the amino acids in proteins, leading to a risk of renal damage.

‘The four phases are confusing — easy enough if you’re a celebrity with a personal chef to weigh out everything for you; harder if you have a job or a family to look after.

‘I call this the Ducan’t diet because the number of people who stick to it is pretty low.’